66647440 has 80 divisors (see below), whose sum is σ = 164721600. Its totient is φ = 25007616.

The previous prime is 66647437. The next prime is 66647453. The reversal of 66647440 is 4474666.

It is a tau number, because it is divible by the number of its divisors (80).

It is a self number, because there is not a number n which added to its sum of digits gives 66647440.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 247626 + ... + 247894.

It is an arithmetic number, because the mean of its divisors is an integer number (2059020).

Almost surely, 2^66647440 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 66647440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (82360800).

66647440 is an abundant number, since it is smaller than the sum of its proper divisors (98074160).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

66647440 is a wasteful number, since it uses less digits than its factorization.

66647440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 464 (or 458 counting only the distinct ones).

The product of its (nonzero) digits is 96768, while the sum is 37.

The square root of 66647440 is about 8163.7883363056. The cubic root of 66647440 is about 405.4411491335.

The spelling of 66647440 in words is "sixty-six million, six hundred forty-seven thousand, four hundred forty".